Paradoxical pigeons are the latest quantum conundrum

First there was Schrödinger's cat, now an international team of physicists has come up with a new animal-related paradox involving "quantum pigeons".

For nearly a century students have struggled to understand the many counter-intuitive implications of quantum physics. Perhaps the most famous paradox is Schrödinger's cat, whereby a cat being both dead and alive at the same time illustrates the fact that a particle can exist simultaneously in two quantum states.

Now, Jeff Tollaksen of Chapman University in California and colleagues in Israel, Italy and the UK have proposed an equally bizarre scenario dubbed the "quantum-pigeonhole effect". The paradox begins with the observation that when you put three pigeons in two pigeonholes, there will always be at least two pigeons in the same hole. But according to the team's quantum analysis, it is possible for none of the pigeons to share a hole.

"It's one of those things that seem to be impossible," says Tollaksen. But it is a direct consequence of quantum mechanics and, he adds, "It really has immense implications."

Nondeterministic measurements

Classical physics is deterministic. This means that measuring the initial state of a system will, in principle, tell you everything you need to determine the final state. But in 1964 Yakir Aharonov of Chapman University and Tel Aviv University helped discover that in quantum mechanics, you can choose initial and final states that are entirely independent, Tollaksen says.

Now Aharonov has teamed up with Tollaksen and colleagues to use this and other concepts of quantum mechanics to postulate the quantum-pigeonhole effect. They reckon that the effect will arise when an observer makes a sequence of measurements while trying to fit three particles in two boxes. First, you make an initial, "pre-selection" measurement of the locations of the particles. Next, you can perform an intermediate measurement to see whether two particles share a box. Finally, you make a final, "post-selection" measurement of the locations. You can make the pre-selection and post-selection measurements such that they are completely independent. In the intermediate step, you can make what's called a weak measurement to look at all three particles simultaneously. And when you do, it turns out that no two particles share a box.

Spooky and profound

The implications of these results, Tollaksen says, complement the well-known Einstein–Podolsky–Rosen (EPR) paradox. In this scenario, two particles that start in the same place can become intimately correlated, a relationship called entanglement. Measuring the state of the first particle seems to influence the state of the second one, even if they are subsequently separated by distances so great that it would be impossible to explain the influence using classical physics. This unsettling conclusion led Einstein to call entanglement "spooky action at a distance".

"EPR is one of the most profound discoveries in science," Tollaksen says. "But that's only half the story." The quantum-pigeonhole principle creates a somewhat opposite situation, he explains. Three particles can begin separated with no connections or correlations at all. You bring them together and force them to interact by squeezing them in two boxes. During this intermediate stage, they are more strongly correlated than classically possible. But in the final stage, they are not correlated at all.

The implications of the EPR paradox are important and shape our understanding of information and the fundamental physics of matter. Although it is too early to predict every implication, he believes that the quantum-pigeonhole principle could prove to be just as influential – if not more so. "This is at least as equally profound, if not more profound," he says. It implies a new concept of correlation that is surprising.

Electronic pigeons

To verify their conclusions, Tollaksen and colleagues propose an experiment in which three electrons travel through an interferometer. This is essentially a beam splitter that creates two separate paths for the electrons, which then meet again.

Because there are only two possible paths, you would expect at least two electrons to share a path. If so, then the two will be close together and interact: their identical electric charges will repel each other, slightly deflecting their trajectories. Then physicists will be able to detect these deflections when all three electrons reunite after the paths converge. But, Tollaksen says, because their calculations show that no two of the three electrons will actually follow the same path, no deflections will be observed.

Physicists have not done these experiments yet, but Tollaksen is confident in their results. "I'm sure it will be confirmed experimentally very soon," he says.

The new results seem "fascinating," says Leonard Susskind of Stanford University. "I would guess that the new effect is a serious step in understanding quantum correlations."

Macroscopic analogy of this situation (note that the interactions of particles are mediated with hyperdimensional longitudinal waves, which are effectively superluminal, so that they cannot be seen)..

Note that despite the whole effect is described with quantum mechanics, it's actually a GR effect instead. The curvature of space-time and it's energy density content is higher at the place, where two particles are present, so that this place weights relatively more than the single particle. Analogously, two Earth planets at close range would weight more than two distant Earth planets due the dark matter effects established at their connection line. For further reading: More is different.

the role of quantum phase

The weak measurements used in the intermediate step perturb the phase only slightly, and consequently do not collapse the wave function and destroy the superposition. Many weak measurements deliver the 'unobservable' phase information.

The causative mechanism for the 'no two pigeons in the same box' paradox presented in this article resides in the time symmetry of quantum phase in the weak measurements.

This was discussed in a study (accepted for presentation at this spring's Berlin conference on quantum information and measurement) of weak measurement results in the nested Mach-Zehnder interferometer. Seevixra.org…1310.0043

If you can't explain something complex in a simple understandable way, you don't understand much of it yourself. This sounds like an attempt to clarify the double slit experiment with light. The energy relationship between any two particles/bodies, no matter the distance between them, that affects any one's state when the other's state changes, can easily be explained in terms of a radio transmitter (tx) and receiver (rx) used as analogy: The energy state (signal) between tx and rx is omnipresent, instant and constant. If tx's state changes, it changes the energy (signal) between it and rx, which then changes rx's state. The focus thus, should be on the state of the "energy" (the link) between them, rather on them themselves. Seek a theory to explain a medium of energy that is able to work a change as is observed. To say they are not in the same box, is to say the "energy" between them is not existent. This should then be explained by the theory as well. This "energy" or "medium" could be called "space-time force" that exists as a constant equilibrium seeking force between two particles/objects.PJ van Staden

Here is a rough example of such a theory;

The positive state space-time force seek equilibrium in the quantum state amongst participating separated bodies to balance the distributed energy mass filling the space-time between it, with non-participating bodies present in the negative state space-time force, and not sharing the same distributed energy mass.

If you can't explain something complex in a simple understandable way, you don't understand much of it yourself. This sounds like an attempt to clarify the double slit experiment with light. The energy relationship between any two particles/bodies, no matter the distance between them, that affects any one's state when the other's state changes, can easily be explained in terms of a radio transmitt.....

Well, double slit experiment can be explained better by reinstating ether into our understanding of Nature. In fact, the experiment can be argued as proof of ether.

The article is a bit incorrect

The article unfortunately makes the same mistake as many other pop-science descriptions of this result do. This is partially due to the Aharonov et al. paper being worded in a really confusing manner. Here is the offending quote from this article: "First, you make an initial, "pre-selection" measurement of the locations of the particles. Next, you can perform an intermediate measurement to see whether two particles share a box. Finally, you make a final, "post-selection" measurement of the locations." This is NOT what's happening. One only performs the first and third experiment. There is NO "intermediate" experiment performed (yes, yes, I know, Aharonov paper's wording seems to suggest otherwise). And if the latter experiment results in a certain state (called |Phi> in Aharonov's paper), then it is non-pigeonholed (meaning any subsequent experiment asking the question "do the particles 1 and 2 (or 1 and 3 or 2 and 3) share one box?" will necessarily yield a "no"). Also, this result, despite pop-sci claims, has nothing to do with future influencing the past. It's in fact an application of really basic, high-school-level almost, quantum mechanical principles. It's VERY subtle but in principle this effect could have been discovered in the 1930s.